Hello,
I recently lived in a bedbug infested apartment that was treated by an exterminator several time, which did not help. Then me and my roommate moved out, because she was allergic to the bites.

We washed everything several times at atleast 60 degrees and dried it really hot as well. What we could not dry hot we put into the freezer for several times. We poured hot water over our suitcases and made sure that not a single egg or bedbug could survive.

However, three weeks after moving, I put on a sweater and have a bug on my arm. I think it was a bedbug nymph, because it was translucent, not red. But when I killed it, there was a little blood (which means that it just fed, or not?) But if it fed a lot, then it would have been darker, because it was really very light.

I have never heard that you find a bedbug climbing on your clothes... and I have only seen one. There are no eggs in my mattress and I also covered the mattress wih a bedbug protector now. I am only assuming that they could be in my clothes, therefore I put them in the freezer now.
Is it possible that I took eggs with me? Or that this was a very small bedbug that survived, that is now growing?
It did seem very confused and also was not full of blood, so I am assuming that it has been in my closet all this time.

Is there maybe another bug that leaves blood behind when being squashed?
A few days ago I also found little grains on the floor(right infront of my housedoor, random place). I squashed them and they left behind a white liquid. Could that have been bedbug eggs as well? (although it was a really random place for eggs (not at all close to my bed, on the floor in the middle of the room)

I am extremely worried that this apartment is infested again. My roommate does not have a rash (yet) which means she has not been bitten yet. I also do not have any bites, but they could still come as they do come later sometimes. She gets the rash the night after she has bitten.

I am sorry that I did not take a picture but I compared it to a nymph when it was still alive and it looked like it, just whiter and not as tiny.

Professional entomologist/arachnologist. I consult on all matters dealing with insects and arachnids, including those of natural history and biology to pest management and forensic entomology investigations.

I will take one in case I see another one. But I am almost 100% sure that it was a bedbug nymph But I am just confused where they are coming from. I do not have bites ever since I moved here, which means that they are not in my room. I cleaned out my closet and did not find any eggs. Is it possible that I just took a nymph with me from the old apartment?

I'm not a professional but that doesn't look like a nymph to me! I can kind of make out a "neck," and that's not visible on bed bug nymphs. Take a look at photos of booklice-- this looks a lot closer to that, in my very amateur opinion.